The present invention relates generally to apparatus suitable for transporting elongate webs or sheets of materials through one or more treatment baths. The apparatus is particularly suitable for use with photographic film developing machinery.
Machines are known which utilize an extended transport roller system for carrying flexible work pieces, such as photographic films or papers. Typical of such machines are those used to develop photographic film. These machines employ a series of treatment baths through which the films are carried in succession by means of transport roller racks which extend downwardly into the treatment bath tanks. The transport roller racks serve to automatically carry the films in a generally U-shaped path through each of the treatment bath tanks. After leaving the last of these tanks, the films pass through another transport roller rack or dryer rack within which they are subject to air flow and sometimes to heat in order to dry the films before they exit from the development machine.
When transporting film through transport roller racks, it has been customary to provide a string of rollers suitably positioned in the rack to transport the film downwardly through a vertically elongated path. The film is then directed through a plurality of turnabout rollers which are positioned near the bottom of the rack and thence urged upwardly through a second vertically elongated path provided by another roller string. Various roller string configurations have been used. On form frequently encountered utilized rollers arranged in a staggered pattern, without forming nips, thereby defining a sinusoidal path for the film between consecutive rollers displaced alternately to one side and the other of the general direction of film movement.
In transport roller racks using such staggered roller pattern, it has been customary to position the rollers at such distance from one another that the individual driving gears at their ends would mesh in a staggered pattern corresponding to that of the rollers themselves. In this way, the gear meshings were between consecutive rollers rotating in mutually opposite directions, and such meshings did not interfere with either gear or roller rotation. On the other hand, as between consecutive rollers rotating in the same direction, the spacing had to be made larger. Large enough in fact to preclude the respective roller driving gears from contacting, let alone meshing; otherwise free rotation of gears and rollers driven thereby would have been impeded. Such spacing relationships are observable, for example, in the above-identified parent applications Ser. Nos. 737,199 and 780,922.